It is desirable to increase thermal conductivity of fuser coating materials to enable higher fusing speed, wider fusing latitude, lower fusing temperature and/or lower minimum fixing temperature. Various thermally conductive fillers have been disclosed for this purpose. As an example, carbon nanotubes (CNT) have been employed in topcoat materials, such as fluoropolymers, to form nanocomposite topcoats. Such materials have demonstrated the capability for increased speed and improved fuser service life. However, it is challenging to develop CNT-in-fluoropolymer composite coatings due to poor compatibility and dispersibility of the CNTs.
Another potential filler material that has recently garnered significant attention is graphene. Graphene is often described as a two dimensional sheet of sp2 bonded carbon atoms arranged in a hexagonal lattice. Due to unique structural features, graphene possesses superior thermal and electrical conductivity, as well as high mechanical strength. Incorporation of graphene into fluoroplastics can improve thermal and/or electrical conductivity and mechanical robustness of the resulting composite material. Both individual graphene sheets and graphene platelets, which include a plurality of graphene layers, show enormous potential as fillers for composite applications. However, it is challenging to make uniform, well-dispersed graphene composite materials with fluoroplastics that are suitable for use in fuser applications. This is due, in part, to properties of graphene in nano-particle form and/or graphene's general incompatibility with fluoropolymers. Phase separations and graphene agglomerations are often associated with poorly dispersed composites, which hinder full utilization of the unique properties of graphene.
Conventional formulations with both graphene and carbon nanotubes include aqueous systems, or require complicated surface treatment processes to produce defect-free composite coatings.
Discovering a novel fluoropolymer composite fuser topcoat material and/or techniques for achieving well dispersed carbon nanotubes and/or graphene in fluoropolymer composities would be a desirable step forward in the art.